East Natuna gas field (formerly known as the Natuna D-Alpha block) is a large natural gas field located in the South China Sea, approximately 225 kilometers (140 miles) northeast of the Natuna Islands and about 1,100 kilometers (680 miles) north of Jakarta, Indonesia. It lies within a maritime area that is disputed between Indonesia and China.
Location and geology: The field is situated in the Greater Sarawak Basin (East Natuna Basin), covering approximately 310 square kilometers (120 sq mi). The reservoir lies at a water depth of 145 meters (476 ft) within the Miocene Terumbu Formation, with a crest at 2,658 meters (8,720 ft) subsea. The formation thickness varies between 300 and 1,525 meters (984 and 5,003 ft).
Discovery and history: The field was discovered in 1973 by the Italian company Agip. In 1980, Indonesia's state-owned oil company Pertamina and Exxon formed a joint venture to develop the field, but development stalled due to the extremely high carbon dioxide (CO₂) content of the gas. In 1995, the Indonesian government signed a contract with Exxon, but the contract was terminated in 2007. The block was awarded to Pertamina in 2008. A new agreement was signed between Pertamina and ExxonMobil in 2010, and the field was renamed East Natuna for greater geographic precision. In 2011, a principal agreement was signed involving Pertamina, ExxonMobil, Total S.A., and Petronas. In 2012, Petronas was replaced by PTT Exploration and Production. As of 2016, negotiations on a new principal agreement and production sharing contract had not been finalized.
Reserves and composition: The estimated gas in place is approximately 222 trillion cubic feet (6.3 trillion cubic meters), with total proven recoverable reserves of 46 trillion cubic feet (1.3 trillion cubic meters). The gas contains approximately 71% CO₂, which presents a major technical and economic challenge for development. Production is forecast to be around 1.98 billion cubic feet per day (56 million cubic meters per day) if developed.
Development challenges: The development of East Natuna is estimated to cost between US$20–40 billion. Production is considered viable only if oil prices exceed approximately $100 per barrel. Proposals have been made for joint development with the nearby Tuna block and South Natuna Sea Block B to reduce costs. As of available information, production was not expected to start before 2030.
Operators and partners: The field is operated by Pertamina, with partners including ExxonMobil, Total S.A., and PTT Exploration and Production.
